3D view of Reull Vallis. The morphology of Reull Vallis suggests it has experienced a diverse and complex history, with analogies seen in glacial activity on Earth. These analogies are giving planetary geologists tantalising glimpses of a past on the Red Planet not too dissimilar to events on our own world todayCourtesy European Space Agency (ESA)
Topographic view of Reull Vallis: The sides of Reull Vallis are particularly sharp and steep in these images, with parallel longitudinal features covering the floor of the channel itself. These structures are believed to be caused by the passage of loose debris and ice during the ‘Amazonian’ period (which continues to this day) due to glacial flow along the channel.The structures were formed long after it was originally carved by liquid water during the Hesperian period, which is believed to have ended between 3.5 billion and 1.8 billion years ago
Reull Vallis: ESA’s Mars Express imaged the striking upper part of the Reull Vallis region of Mars with its high-resolution stereo camera last year. Reull Vallis, the river-like structure in these images, is believed to have formed when running water flowed in the distant martian past, cutting a steep-sided channel through the Promethei Terra Highlands before running on towards the floor of the vast Hellas basin.
Perspective view of Reull Vallis: A region of Reull Vallis at a point where the channel is almost 7 km wide and 300 m deepCourtesy European Space Agency (ESA)
This perspective view shows one of the mountains in the Promethei Terra Highlands with nearby sediment-filled impact cratersThis region shows a striking resemblance to the morphology found in regions on Earth affected by glaciation. For example, we can see circular step-like structures on the inner walls of the sediment-filled crater in the foreground of the second perspective view. Planetary scientists think that these may represent former high water or glacial levels, before ice and water sublimated or evaporated away in stages at various times
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